Age-related macular degeneration (AMD) is a major human blindness disease. It often leads to central vision loss during an attack, and even makes blindness seriously. The incidence of age-related macular degeneration associates with ages. The disease easily happens with getting older. The survey shows that 15 million people having more than 50 years old are suffering from this disease in North America, 1.2 million people of which are in serious condition. 30% of population over 75 years in the United States is suffering from macular degeneration in certain degree, and 23% of population over 75 years in the United States will suffer from macular degeneration in next five years. Some surveys show that the incidence of macular degeneration is respectively 16.8%, 25.6% and 42% for the age of 55-64, 65-74 and over the age of 75 of people.
There are two types of un-exudative (dry) and exudative (wet) macular degeneration. The two types of macular degeneration reflect different pathological processes, and usually occur on the two eyes of patients simultaneously, and it will develop deeply if without intervention.
Both of the dry and wet macular degeneration are accompanied with formation of drusen in eyes. Drusen is a kind of small spots from irregular round yellow to white frogspawn, transparent or translucent between retinal pigment epithelium and Bruch's membrane. The drusen always means pathological changes of retinal pigment epithelium function. The drusen has two of hard and soft forms. The hard drusen (tuberculiform) is due to accumulation of retinal epithelial cells metabolism fragment on the Bruch's membrane. The soft drusen is generally larger than the hard drusen and without clear boundary, and is usually formed by shed of retinal epithelial cells. The drusen will light after calcification. Dry macular degeneration often leads to atrophy and degeneration of external retinal, retinal epithelial cells, Bruch's membrane or choriocapillaris, to form drusen, color disorder and other eyes dysfunction. The wet macular degeneration is characterized in that pulpiness or hemorrhagic detachment of retina epithelial cells or sensory nerve layers, will lead to formation of choroidal neovascularization. These could cause visual distortion or blurred central vision in clinic, seriously may result in blindness.
As mentioned above, AMD is eye diseases resulting in blindness. This is because a fluorescent lipofuscin formed by lipid oxidation in eyes, leads to formation of drusen, Bruch's membrane and choroidal neovascularization. It is believed that eyes exposed to high energy blue light for long-term can accelerate lipofuscin formation. At present, the mechanism of AMD formation is unclear, no specific method of treatment or prevention is provided. However many researches show that formation and development of AMD closely relates to amounts of carotenoids in eyes, especially contents of lutein and zeaxanthin. Large amount of lutein and zeaxanthin can delay occurrence and formation of AMD. In addition, antioxidants of the body such as vitamin E, vitamin A, selenium, zinc and glutathione can also play an inhibitory effect on the development of AMD.
Lutein and zeaxanthin are merely two carotenoids in the human retina and are selectively deposited in macular region and the retina, have the highest density around the macular fovea center and a gradually decreased density around the retina. These macular pigments can effectively prevent from occurrence of oxidation reaction in retina. It could be assumed that an effective method of treating or preventing macular degeneration or injury is to supple for lutein and zeaxanthin. The good health effect on AMD made by lutein and zeaxanthin is mainly because lutein and zeaxanthin have the maximum absorption wavelength around 450 nm to be consistent with the blue light wavelength in visible light. Lutein and zeaxanthin in fundus macular can have a good filtering effect to absorb and filter destructive blue lights, in order to protect eyes and reduce lipid oxidation, delay occurrence and development of AMD. Furthermore, lutein and zeaxanthin can be used to improve visual efficacy such as juvenile myopia and senile blindness caused by muscle degeneration and eye damage caused by the ultraviolet radiation from sunlight and computer in the absence of AMD. Lots of clinical tests results show that the intake of lutein and zeaxanthin is 6 mg per dayin human body. It is thought that the carotenoid yellow dermatosis could not bring about if the acceptable daily intake (ADI) of lutein crystal is 25 mg/person/day.
More and more people are interested in special physiological functions of lutein and zeaxanthin. Currently, a large amount of healthy food and fortified food containing two natural pigments of lutein and zeaxanthin are present abroad. The FDA of USA approved uses of lutein and zeaxanthin as food supplement agents to improve nutritive values in 1995.
Lutein and zeaxanthin can't be synthesized in human body and must be ingested from outside. Currently lutein can only be extracted from plants mainly marigold flowers due to its asymmetry structure. Zeaxanthin is mainly derived from three sources such as extracting from matrimony vine plants, chemical synthesizing and obtaining by lutein isomerization transposition reaction. Zeaxanthin extracted from plants and by chemical synthesis is (3R, 3′R) stereoisomeric zeaxanthin. The one obtained from isomerization of lutein is (3R, 3′S) isomer. Both of (3R, 3′R)-zeaxanthin and (3R ,3′S, meso)-zeaxanthin are distributed in human eyes, in particular, the proportion of (3R , 3′S, meso)-zeaxanthin close to the visual center is higher.
More and more people are engaged in researches of lutein and zeaxanthin and many products of treating and preventing fundus macular degeneration (AMD) through lutein and zeaxanthin are present in the market, based on understanding on function and perfection of laws of lutein and zeaxanthin for visual health. These studies or products often focus on functions of lutein and zeaxanthin. However it hasn't reported that the complex use of lutein and zeaxanthin, especially lutein cooperating with large amount of zeaxanthin, and a certain amount of plant polyphenols antioxidants is used to treating or preventing AMD.
U.S. Pat. No. 7,282,225 B1 discloses a dietary supplement comprising various vitamins, minerals, carotenoids, antioxidants and plant extracts. The dietary supplement is beneficial to enhance visual function and acuity, and is helpful to treat or prevent macular degeneration. Wherein it uses a variety of plant extracts to be limited, and complex composition, and but it doesn't notice special efficacy of zeaxanthin.
US 2009/0155381 A1 describes a medication comprising lutein and/or zeaxanthin and many antioxidants for treating or preventing age-related macular degeneration. But this formula does not mention the important role of zeaxanthin in visual health.
US 2009/0181901 A1 introduces a substance containing—SH functional group or the mixer thereof with anthocyanin used for increasing the bioavailability of carotenoid including lutein in body.
US 2010/0330171A1 describes a nutritional supplement contributing to visual health, consisting of an anti-oxidant component, an anti-inflammatory component and an anti-angiogenic component, wherein the supplement comprises tocotrienol and green tea extract.
U.S. Pat. No. 7,887,847 B2 reveals a dietary component comprising vitamin E, minerals, polyunsaturated fatty acids, lutein and zeaxanthin. Wherein the weight ratio of lutein to zeaxanthin is around 20:1 and the amount of zeaxanthin is less.
U.S. Pat. No. 7,267,830 B2 presents a dietary supplement for delaying macular degeneration and improving visual health, comprising vitamin E, lutein and zeaxanthin, copper, zinc, DHA, rosemary extract and other vitamins and minerals, etc., the formula is complicated, and the weight ratio of lutein to zeaxanthin is around 2:1.
U.S. Pat. No. 6,329,432 B2 analyzes distribution of zeaxanthin stereoisomer in human eyes. It is considered that the content of zeaxanthin is higher close to the macular center relative to lutein, especially the content of meso-zeaxanthin in the visual macular reaches the highest concentration at the midpoint of macular center. It implies that they play an important role in visual health especially in delaying processes of AMD diseases. But it only emphasizes effects of meso-zeaxanthin of preventing or treating AMD in the patent, neither reminds synergistic effects of zeaxanthin and lutein, nor reminds synergistic effects of other substances.
All of the above applications or patents are to provide dietary supplements mixing one or several vitamins, antioxidants, plant extracts with lutein and zeaxanthin, to act as effects of delaying or treating macular recession. But it just emphasizes functions of lutein in these formulas, no deeply researches on eyes' function of zeaxanthin is provided. In fact, zeaxanthin has one conjugated double bond more than lutein in molecular structure, it makes zeaxanthin have stronger antioxidant activity than lutein, and plays an important role in human visual health. Some researches in 1980's also proved that substances in the eye macular center is mainly zeaxanthin, the amount of zeaxanthin gradually reduces, the amount of lutein subsequently increases when concentrically away from recess and close to the outer peripheral of the macular, and lutein is the major yellow pigment in the periphery of the macular.
It can also be seen from changes of proportion of lutein to zeaxanthin in nature and different parts of body tissues that the proportion of lutein to zeaxanthin in marigold flowers of lutein raw materials is around 10˜12:1, this proportion in human blood is around 3˜5:1, the proportion of lutein to zeaxanthin in the macular periphery is 3:1, but, the proportion of lutein to zeaxanthin in the macular center is completely reversed and is 1:3, The change of the proportion of lutein to zeaxanthin in the different parts of the eyes shows that the zeaxanthin especially meso-zeaxanthin plays an important and unique role in human visual health. If the proportion of lutein to zeaxanthin in dietary supplement  would be determined by the proportion of lutein to zeaxanthin in macular center, it would strengthen the concentration of zeaxanthin in eyes and would play better effects of delaying AMD.
In addition, it would play unexpected effects when moderately adding some plant extracts in order to prevent or delay formation of choroidal neovascularization caused by pulpiness or hemorrhagic detachment of the retina epithelial cells or sensory nerve layers before and after AMD disease. Green tea extracts among these plant extracts would be worth watching. Green tea polyphenols mainly comprises four components such as GC (gallocatechin), CG (catechin gallate), GCG (gallocatechin gallate). The epigallocatechin gallate (EGCG) has the highest activity in the green tea polyphenols. Epidemiological studies revealed that EGCG has the ability of resisting formation of blood vessels and reduces the incidence of diabetes proliferative vascular hyperplastic lesions. Angiogenesis in ocular neovascularization is of great significance for damage of structure and function of the eyes. It is further found that green tea polyphenols can significantly inhibit proliferation of endothelial cells in a dose-dependent manner, and can lead to cell arrest in G1 phase. So green tea polyphenol is one of effective and prospective drugs of anti-angiogenesis.